Recent In Internet. Prestressed Concrete is basically concrete in which internal stresses of a suitable magnitude and sitribution are introduced so that the str A type of foundation often used at the base of a column. It consists of one, two or more tiers of steel beams superimposed on a layer of con Unsteady flow and sediment transport will be added in future versions. The NexGen project encompasses several aspects of hydrologic engineering, including: rainfall-runoff analysis; river hydraulics; reservoir system simulation; flood damage analysis; and real-time river forecasting for reservoir operations.
Each document is designed to help the user learn to use a particular aspect of the modeling system. The manual provides an introduction and overview of the modeling system, installation instructions, how to get started, simple examples, detailed descriptions of each of the major modeling components, and how to view graphical and tabular output.
Equations are presented along with the assumptions used in their derivation. Discussions are provided on how to estimate model parameters, as well as guidelines on various modeling approaches. Each example consists of a problem statement, data requirements, general outline of solution steps, displays of key input and output screens, and discussions of important modeling aspects. The discussions in this manual contain detailed descriptions for the data input and analysis of the output for each example.
The examples display and describe the input and output screens used to enter the data and view the output. The user can activate the projects within the HEC-RAS program when reviewing the descriptions for the examples in this manual.
All of the projects have been computed, and the user can review the input and output screens that are discussed as they appear in this manual. The user can use the zoom features and options selections plans, profiles, variables, reaches, etc. The examples are intended as a guide for performing similar analyses.
This manual is organized as follows: This river reach is situated on a steep slope, and the analysis was performed in a mixed flow regime to obtain solutions in both subcritical and supercritical flows. Additionally, the example describes the procedure for cross section interpolation.
The data entry for the bridge and determination for the placement of the cross sections are shown in detail. Additionally, the model is calibrated with observed high flow data. Additionally, a review for the locations of the cross sections in relation to the culvert is presented.
The second culvert also contains two identical barrels, and this example describes the review of the output for multiple culverts. The user should be familiar with individual bridge and culvert analyses before reviewing this example. An example procedure for the floodplain encroachment analysis is performed.
The user should be aware of the site specific guidelines for a floodplain encroachment analysis to determine which methods and the appropriate procedures to perform. The concepts of working with projects and plans to organize geometry, flow, and other files are described. Then, an application is performed to show a typical procedure for organizing a project that contains multiple plans. The loop is a split in the main channel that forms two streams which join back together.
The example focuses on the procedure for balancing of the flows around the loop. The bridge crossing constricts the main channel supercritical flow, creating a subcritical backwater effect, requiring the use of the mixed flow regime for the analysis.
Results by subcritical and supercritical flow regime analyses are presented to show inconsistencies that developed, and to provide guidance when to perform a mixed flow analysis. This example illustrates a flow combining of two subcritical streams, and both the energy and momentum methods are used for two separate analyses. The user should be familiar with the procedures for modeling bridges before reviewing this example.
The scour equations and procedures are based upon the methods outlined in Hydraulic Engineering Circular No. Procedures for entering the data to provide flexibility for the flow analysis are provided. This example has a split of flow at a junction, as well as a lateral weir. Channel modifications are performed, and existing and modified conditions geometry and output are compared. Discussions include: entering storage area information; hydraulic connections; unsteady flow data boundary conditions and initial conditions ; performing the computations; and reviewing the unsteady flow results.
Additionally, the example will demonstrate the need for additional cross sections for a more accurate estimate of the energy losses and water surface elevations. This will activate the Geometric Data Editor and display the river system schematic, as shown in Figure 1. As shown in the figure, the river name was entered as "Critical Creek," and the reach name was "Upper Reach.
These cross-section identifiers are only used by the program for placement of the cross sections in a numerical order, with the highest number being the most upstream section. Most of the 12 cross sections contain at least 50 pairs of X-Y coordinates, so the cross section data will not be shown here for brevity.
The distances between the cross sections are as shown in Figure 1. Example 1 Critical Creek 12 can be seen by using the scroll bars in the window.
Example 1 Critical Creek Figure Reach Lengths For Critical Creek From the geometric data, it can be seen that most of the cross sections are spaced approximately feet apart.
The change in elevation from cross section 12 to cross-section 1 is approximately 56 feet along the river reach of feet. This yields a slope of approximately 0. Also, the coefficients of contraction and expansion are 0.
After all the geometric data was entered, it was saved as the file "Base Geometry Data. For this steady flow analysis, the one percent chance flow profile was analyzed. A flow of cfs was used at the upstream end of the reach at section 12 and a flow change to cfs was used at section 8 to account for a tributary inflow into the main river reach. This flow change location was entered by selecting the river, reach, river station, and then pressing the Add A Flow Change Location button.
Then, the table in the central portion of the editor added the row for river station 8. Finally, the profile name was changed from the default heading of "PF 1" to " yr.
This value was estimated as the average slope of the channel near the downstream boundary. For a subcritical flow analysis, boundary conditions must be set at the downstream end s of the river system. After all of the flow data was entered, it was saved as the file " Year Profile. Before performing the steady flow analysis, Options and then Critical Depth Output Option were selected. The option Critical Always Calculated was chosen to have critical depth calculated at all locations.
This will enable the critical depth to be plotted at all locations on the profile when the results are analyzed. Next, the Flow Regime was selected as "Subcritical". The geometry file was selected as "Base Geometry Data," and the flow file was selected as " Year Profile". This activated the water surface profile as shown in Figure 1. From the Options menu, the Variables of water surface, energy, and critical depth, were chosen to be plotted.
Figure Profile Plot for Critical Creek From this profile, it can be seen that the water surface appears to approach or is equal to the critical depth at several locations. For example, from Example 1 Critical Creek section 12 through 8, the water surface appears to coincide with the critical depth. This implies that the program may have had some difficulty in determining a subcritical flow value in this region, or perhaps the actual value of the flow depth is in the supercritical flow regime.
Stream Junctions. Bridges and Culverts. Storage Areas. Pump Stations. Cross Section Interpolation. River Ice. Viewing and Editing Data through Tables. Importing Geometric Data. Geometric Data Tools. Geometric Data Options. Attaching and Viewing Pictures. Saving the Geometric Data. However, switching back and forth between diffusion wave and full momentum is easy.
I'd suggest trying both and seeing what the differences are. My river profile is not showing in geometic window,. Please help as without profile generation, geometic data input will not be started…My river length is km with number of cross sections. Your email address will not be published.
Save my name, email, and website in this browser for the next time I comment. Ben Cary,. Chris Goodell,. Grady Hillhouse,. Practical Engineering,. The RAS Solution,. RAS Mapper,. RAS Results,. RASter Calculator,. Visual Basic,. Example Projects,. File Management,. Emmanuel Jjunju on December 17, After running my simulation, i dont see nay results in ras mapper.
Chris Goodell on December 17, Are you checking all of the boxes in the layer manager? Chris Goodell on January 4, Yes.
0コメント